In many military applications as well as some commercial applications, welding is to be performed by a SMAW electrode in a manner to produce a high yield strength. The electrode used in these applications must produce a yield strength in the general range of 85 ksi to 125 ksi. To accomplish such high yield strength, the coating of the stick electrode must have substantial amounts of alloying agents, such as nickel, manganese and molybdenum. The yield and tensile strength for any given alloy are determined by the cooling rate, as it relates to the continuous cooling transformation curve (CCT) of the particular steel alloy. The strength of the weld metal bead as well as the cooling rate sensitivity relates to the composition, as well as the carbon content of the steel and the actual cooling rate for the molten and solidified weld metal. It has been found that the cooling rate changes drastically according to the thickness and preheat of the workpiece and the amount of electrical energy used in the shielded metal arc welding process. It is desirable to minimize the yield strength sensitivity to the different cooling rates, while maintaining the alloy composition of the weld metal so that the high yield strength in the range of 85 ksi to 125 ksi can be assured in the resulting weld. Consequently, there is a need to create a stick electrode that minimizes the cooling rate sensitivity so the resulting weld is within the high yield strength specification for both an extreme high cooling rate and an extreme low cooling rate.
Additionally, currently all high strength electrodes used for welding high strength steels, have chromium (Cr) added to the electrode composition to increase the tensile and yield strength of the weld. However, because Cr is added to the electrode composition, Cr is emitted as fume during the welding operation. This Cr emission can be hazardous, thus causing the Occupational Safety and Health Administration (OSHA) and American Welding Society (AWS) to mandate limits on the amount of hexavalent Cr present in the welding fumes. Therefore, there is a need for a welding electrode which is capable of being used for creating high strength welds, which has no Cr added to the electrode composition.